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Much higher chlorine than expected

I have a 25000 gallon pool that has been full since the end of July and running with the SWG since the beginning of September. I have been slowly tuning the numbers but have been increasingly more troubled by the SWG settings vs CL output.

I have an IC-40 that was purchased by me on eBay and installed by the PB. It has been on since day 1 but wasn't producing chlorine until I dumped the salt in starting on 9/4. This all seemed very normal to me. After I dumped the salt in and tuned the Intelliflow for enough flow to keep the flow light green I thought I was in business.

The PB had set the initial SWG output to 80% which resulted in CL levels of near 10. I have been slowly reducing the SWG output and then testing the CL levels a day or two later and repeating. I am now at a point that makes me suspicious that something is not right. Please note that due to cold temps we have not been swimming for about 30-35 days so swimmer load is not a factor. Also there is little to no organic material entering the pool. My 4X160 has been running at 1300RPM from 7:00AM until 3:00PM seven days a week for many weeks now. The water has always been crystal clear.

Here's the latest full set of numbers taken with the TF100
FC........7.0
CC........0.0 It's never been anything but 0.0
TC........7.0
pH........7.5 I keep it between 7.4-7.6
TA.......100
CH.......330
CYA.......80
SALT...3500 Not measured since adding 50# last weekend
TEMP......60

Ok that's all the background info...now for the questions. Do I have a problem with my SWG? Is it normal to run at 3% and still get a CL of 7.0?

Re: Much higher chlorine than expected

Two nights ago I changed from 2% to 1% and still measured 6.5ppm last night. I am running 8 hours. I may have to try and only run the SWG for part of the total pump time if that's possible. I suppose I could just dial the speed down so the flow switch shuts the SWG off.

Re: Much higher chlorine than expected

I too had/have the same issue.

I got salt in the pool at the beginning of September and the PB set the IC40 to 80%. The chlorine was well over 10 ppm in no time. I lowered to 60%, then 40%, 20%, 10% and just lowered to 8%. I'd bet I end up at about 3-4% once I'm done, I just don't want to lower it too much (as Jason said, it may take a while to adjust). Until today, it's been covered, with no swimmers for a month, no organics, but a load of dirt from the landscaping.

I run the pump for 1 turn/day. This is 15 gpm for the cleaner for 4 hours overnight and about 28 gpm for 12 hours during the day. I'm not sure it the SWG is working while it's being cleaned at night (15 gpm) -- I'm usually not awake at 2:00 AM through 6:00 (except when the cleaner climbs out of the pool and I awake to a giant sucking sound and the pump re-priming.

The IC40 is oversized for the pool. A good lesson for those looking at it but not considering the Intellitouch or similar controllers. If not, then it would be 20% or nothing.

Re: Much higher chlorine than expected

Kevin,

I checked, and the SWG is off at night at 15 gpm (not surprisingly). The manual states 20 gpm is the minimum. The way it's chlorinating, I'm not sure I want itt running at night -- the less the better. But seriously, I believe it's better at 2% all the time instead of 4% half of the time -- more even flow of chlorinated water entering the pool.

I'm overchlorinated at 10% 12 hours a day (72 minutes of SWG total).

Am I doing my math right? If the SWG has a 10,000 hour life and it runs for 8% a day for 12 hours (1 hour on/day) that works out to a 27 year lifespan.... seems pretty high. I'd guess that it'll fail some other say before then, but I'll be happy if I get 10 years.

Re: Much higher chlorine than expected

The amount of Chlorine needed is directly related to pool water temp. It goes down very fast
with water temp. Water temp of 65 deg needs little chlorine added to maintain the
chlorine level. The opposite when the water temp increases. Above 78 deg the amount
of chlorine needed raises rather rapidly with water temp.

Many of the SWG's have a temp. compensation built in to slow down chlorine
generation as the water temp. falls. If yours doesn't have this feature
then you will have to run the SWG a shorter amount of time or turn down the
output.

Be sure to write down the settings you need, then all you will have to do is change the
settings with the seasons. It will take w while to come up with the settings that work with
your pool, seems as though every pool is a little different.

Re: Much higher chlorine than expected

I may be mistaken, but AutoPilot is the only one with the automatic temperature compensation, as it's a patented feature.
Having said that, everyone elses system has a cold temp cut off, that shuts down the system when it gets too cold...except AutoPilot. We lower the output to 1% at around 55 degrees or colder.

The mechanics of the salt generation process does "reduce" the amount of chlorine produced slightly due to the cold temps, but is not a temperature compensation. That's why you have to manually adjust the output of the system as it gets colder with other systems, otherwise you tend to overchlorinate...which takes us back to the original post.

Re: Much higher chlorine than expected

Sean,

As I understand it, the reason other units cut off at cold temps is that the cell is unable to do the math on what the salt level of the water is. Does the AutoPilot still measure salt levels accurately below 55 degrees or does it default to 1% because there's little risk of damage at that production level even if the salt is too low/high?

Re: Much higher chlorine than expected

I think I will reduce the run time from 8 hours down to 6 and see what happens. I'm shooting for a CL of about 4. If the CL drops lower than 4 I'll just bump the SWG up a bit.

Hmmm. At 1%, 'bumping up the SWG a 'bit' is doubling its output by setting it at 2% -- might have to be an adjustment in run-time. But I know what you mean. I'll check mine this weekend -- it's at 4 % now.

Re: Much higher chlorine than expected

Originally Posted by spishex

Sean,

As I understand it, the reason other units cut off at cold temps is that the cell is unable to do the math on what the salt level of the water is. Does the AutoPilot still measure salt levels accurately below 55 degrees or does it default to 1% because there's little risk of damage at that production level even if the salt is too low/high?

Thanks!

Tim

There are few systems that have true salinity sensors to prove an accurate salt reading. Most are determined by estimating the salt level, based on the cell amps and volts. The AutoPilot's salt sensor is temperature compensated so it it stays accurate under cold water conditions.

The reason most systems cut off under cold water temperatures is that the the electrolytic reaction starts to make more oxygen than chlorine, there's slightly more wear on the cell if the output setting is not reduced (cell run time), and the cell voltage tends to increase (causing a higher power load on the power suppy). So you can see that there is, in fact, more damage that can occur at cold water conditions on the cell and the power supply. Thus the cold temp cutoff.
However, adding more salt to maintain the upper end of the recommended salt level, can help a cell continue to operate under cold water conditions that would normally turn off the cell.